Sheet feeding means for roll forming mill



Oct. 13, 1970 c. H. GUENTHER ETAL 3,

SHEET FEEDING MEANS FOR ROLL FORMING MILL Filed July 26, 1968 6 Sheets-Sheet l LL. K

. INVENTORS r0. 1 CLIFFORD H. GUENTHER I I BY RENE G. BEAUVAIS (\l w O I I. r M (1111 14 I Y m L WYYZM Oct. 13, 1970 c. H. GUENTHER ET AL 3,533,619

SHEET FEEDING MEANS FOR ROLL FORMING MILL INVENTORS CLIFFORD fl. GUENTHER RENE G.

Oct. 13, 1970 c. H. GUENTHER ET AL 3,533,619

SHEET FEEDING MEANS FOR ROLL FORMING MILL Filed July 26, 1968 a Sheets-Sheet 3 FIG. 3.

' INVENTORS CLIFFORD, HQGUENTHER RENE G. BEAUVAIS BY MW-MMV Oct. 13, 1970 c. H. GUENTHER ET AL 3,533,519

SHEET FEEDING MEANS FOR ROLL FORMING MILL Filed July 26, 1968 6 Sheets-Sheet 4 INVENTORS WM Oct. 13, 1970 C. H. GUENTHER ETAL SHEET FEEDING MEANS FOR ROLL FORMING MILL.

Filed July 26, 1968 6 Sheets-Sheet 5' FIG. 6.

III

III!

INVENTORS CLIFFORD H. GUENTHER BY RENE G. BEAUVAIS Oct. 13, 1970 c. H. GUENTHER ET AL 3,533,619

SHEET FEEDING MEANS FOR ROLL FORMING MILL Filed July 26, 1968 6 Sheets-Sheet 6 FIG. IO.

INVENTORS CLIFFORD H. GUENTHER RENE G. BEAUVA W W 4mm) 2 75M z' fhwa United States Patent 3,533,619 SHEET FEEDING MEANS FOR ROLL FORMING MILL Clifford H. Guenther and Rene G. Beauvais, Bay City, Mich., assignors to Resistance Welder Corporation, Bay City, Mich, a corporation of Michigan Filed July 26, 1968, Ser. No. 748,018

Int. Cl. B6511 9/10 US. Cl. 27155 24 Claims ABSTRACT OF THE DISCLOSURE Apparatus and methods for accomplishing the aligned feeding of prenotched sheet metal blanks, which have longitudinal camber, at right angles to a pair of rolls, and wherein notch entering sheet clamping members are provided on carriages which have a precise forward travel and the sheet is driven forwardly but can move only in a precise path dictated by the carriages.

This invention relates particularly to the appliance field where prenotched and pierced sheets are roll formed, and then subsequently U-fold formed in the manufacture of refrigerator cabinets. The relationship of the notches and holes to the roll formed flanges is highly critical, and it has been past practice, in order to hold this relationship, that all individuals sheet-s had to be resquared to insure a straight sheet edge which could then be used as a gauge for both the notching and roll forming operations. This resquaring has been required to eliminate the camber which is present in all coiled sheet stock.

An object of the present invention is to eliminate the need for resquaring guide edges of the sheets with the cost savings incident thereto by providing sheet or blank feeding apparatus which assures that each sheet is brought to the roll forming machine in properly squared alignment.

A further object is to provide means whereby the sheet is guided into a plurality of roll stands on the mill in a manner to insure against side drift of the trailing end of the sheet.

Another object of the invention is to design and develop a roll forming mill feed table which registers off the notches in the sheet, instead of using the sheet edge as a guide. This provides a two-fold advantage in eliminating the need for resquared guide edges and the costsavings incident thereto, and in insuring that the bend notches are in proper location for subsequent U-folding and welding operations. Experience with the table dictates that the sheet metal blanks must be guided into a plurality of roll stands on the mill to insure against side drifting of the trailing end of the sheet. The two rear notches on each side of the sheet have therefore been established as guide points, thus providing sufficient wheel base for true feeding alignment, while allowing at least the first three mill stands to engage the sheet before removal of the first notch locator. In practice, approximately six mill stands engage the sheet before the second and last notch locator is released.

With the above and other objects in view, the present invention consists in the combination and arrangement of parts, hereinafter more fully described, illustrated in 3,533,619 Patented Oct. 13, 1970 the accompanying drawings, and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportion and minor details of construction, without departing from the spirit, or sacrificing any of the advantages of the invention.

In the drawings:

FIG. 1 is a side elevational view of the apparatus with the sheet aligning carriages shown in rearmost position in solid lines, and foremost position in chain lines.

FIG. 2 is an enlarged, fragmentary, transverse sectional view, taken on the line 22 of FIG. 1, with certain parts omitted in the interests of clarity.

FIG. 3 is a slightly enlarged, fragmentary, top plan view, with certain parts again omitted in the interests of clarity.

FIG. 4 is a perspective side elevational view on an enlarged scale, illustrating the construction of the aligning carriages, and particularly the front carriage.

FIG. 5 is an enlarged, fragmentary, side elevational view showing the apparatus with the lead carriage illustrated in foremost position.

FIG. 6 is a top plan view showing the upper locator member releasing cam track.

FIG. 7 is an enlarged, fragmentary, top plan view illustrating particularly the sheet stop which is used to initially locate the sheet on the table.

FIG. 8 is a fragmentary, side elevational view illustrating a whip restraining clamp assembly which is provided on the rear carriage.

FIG. 9 is a perspective elevational view of the refrigerator cabinet part after it emerges from the forming and bending apparatus which is downstream of the sheet advancing apparatus of the present invention in the manufacturing line.

FIG. 10 is a schematic electrical control circuit illustrating the manner in which the various operating elements may be typically controlled.

Referring now more particularly to the accompanying drawings in which we have shown a preferred embodiment of our sheet advancing or feeding apparatus only, a letter F generally designates a frame or base which may comprise support posts or legs 10 connected at their upper ends by rails 11 and intermediately by rails 12. Spanning the upper side rails 11 is a support plate 13 which mounts support blocks 14 for bearings 15 which journal the longitudinally spaced shafts 16 on which a series of magnetic drive rollers 17 are mounted as shown. The rollers 17 are employed to move the blank or sheet B in a manner which will later be described, over a support table, generally designated 18, and extending substantially from one end of the machine to the other, which includes a series of freely rotatable rollers 19. The rollers 19 are journaled on shafts or pins 20, the pins 20 being supported on side rails 21, mounted by crossbraces 22 on post members 23 which are fixed on the support plate 13.

As has been indicated, the sheet metal blank B, which has longitudinal camber, has been preformed with precisely located and formed notches 24-26 on one edge of the sheet and 27-29 on the opposite edge of the sheet. Thus, the notches 25 and 26 and 28 and 29 may be utilized to position the sheet B relative to the forming roll mechanism, generally designated 30, which is utilized for forming upstanding flanges x on the longitudinal edges of the sheet B (see FIG. 9). As FIG. indicates, the roll forming machine includes a pair of infeed rolls 31 and 32 which feed the sheet B to a series of flange forming rolls or roll stands (not shown) which form no part of the present invention, and are not therefore shown. The flange forming mechanisms may comprise a conventional flange rolling machine of the Yoder type, manufactured by the Yoder Company of Cleveland, Ohio. As has been indicated, the blank B must be fed through the flange forming machine so that the sides or edges of the blanks are exactly at right angles to the forming rolls in order to properly flange the edges of the sheet B, and must not move out of this alignment in its longitudinal travel.

Mounted on the frame F to insure accurate and aligned longitudinal travel of the sheet B, in a manner which will be explained, is a fixed carriage guide assembly including a guide rod 33 which is fixed on longitudinally spaced riser brackets 34 on one side of the table apparatus. On the opposite side of the plate 13 a longitudinal channel guide 35 is provided, supported on longitudinally spaced apart support posts 36. Mounted for reciprocating longitudinal movement along the guide rod 33 and guide member 35 are sheet aligning front and rear carriages, generally designated 37 and 38, respectively. FIG. 4 well illustrates the construction of the fabricated carriages, and it should be understood that, since each of the carriages is constructed substantially in the manner shown in FIG. 4, it will be necessary only to specifically describe the front carriage. As FIGS. 2 and 4 indicate, the front or leading carriage 37, which has a top plate 37a extending across the machine above the sheet B and which may typically be fabricated of aluminum stock, includes dependent bearing housing 38a at one side, incorporating ball slide bushings 39 which mount the carriage 37 for longitudinal travel on the guide rod 33. Mounted on the opposite side of the carriage 37 is a dependent arm 40 supporting at its lower end a plurality of rotatable guide rollers 41 which travel in the guide track member 35.

As FIG. 2 particularly indicates, the carriage 37 also includes a transversely extending rocker arm 42, journaled on a pin 43 and supported by a clevis block 43a which has a hardened specially shaped locator insert or sheet gripping clamp member 44 secured on its inboard end which is shaped to engage in the notch 25 (FIG. 3). The rocker arm 42 is movable from the generally horizontal sheet engaging position in which it is shown in solid lines in FIG. 2 to a released or disengaged positon which is illustrated by the broken lines in FIG. 2. Supported on the carriage 37 to operate the rocker arm 42 is a double-acting solenoid operated fluid pressure cylinder 45, having a piston rod 46 which connects to the rocker arm at 47. At its upper end, the cylinder is connected as at 48 to the bracket 49 which is welded or otherwise suitably fixed to the carriage plate 37a.

At the opposite side of the carriage 37 a generally vertically extending rocker arm 50 is pivotally mounted on a pin or shaft 51. The pin 50 is supported by a clevis block 52, mounted on a slide plate 53 (see FIG. 4) which is fixed in various adjusted positions, depending on the width of the particular blank B which is being forwarded. The slide 53 is mounted in transversely extending gibs 54 provided on the carriage top plate 37a, and a doubleacting, solenoid actuated, fluid pressure cylinder 55 is connected as at 56 to a support block 57 on the plate 53. The piston rod 58 of the cylinder 55 connects to the upper end of the rocker arm 50 as at 59. At the lower end of rocker arm 50 a specially shaped hardened insert or sheet gripping clamp member 60 is provided which is shaped to engage in the notch 28 as shown in FIG. 3, when the rocker arm 50 is pivoted to the position in which it is shown in solid lines in FIG. 2. As shown in FIGS. 2 and 4 particularly, pairs of hold-down rollers 61 are provided at each side of the carriage, mounted on shafts 62 which are supported by depending brackets 63.

Provided to positively return the rocker arm 42 to inoperative position and release the insert 44 from the notch 25 when the carriage 37 nears its foremost position is a cam 64a supported from the frame F by a brace 64b. The cam 64a is positioned to be engaged by a cam follower member 64 which is rotatably supported on a pin 65 fixed on a lug 66 depending from the arm 42. Similarly at the opposite end of the carriage 37, the rocker arm 58 is returned to inoperative position by a cam 67a supported from the frame F by braces 67 b. The cam 67a is positioned to be engaged by a cam follower roller 67 rotatably mounted on a shaft 68 supported by a bracket 69 on the rocker arm 50.

It isto be understood that the carriage '38 is identical to the carriage 37 insofar as the carriage 37 has been described, except that it is of opposite hand and accordingly the carriage 3 8 will not be specifically described and like numerals will be employed to identify the various like parts. The cams 64a and 67a operate to release the rocker arms 42 and 50* of each carriage. Each carriage also employs cushioned stop 70 which, as FIGS. 4 and 8 indicate, extends forwardly from the carriage. The stop 70 on carriage 37 is in alignment with a fixed stop member 71 provided on a plate 72 which secures to the support plate 13 and functions to positively halt the forward travel of the carriage 37. The stop 70 on the rear carriage 38 is in alignment with the carriage 37 and functions similarly to positively halt the carriage 37 in the foremost position.

Mounted on the rear carriage 38 only is a vertically moving clamp member 73 having a hardened sheet engaging insert 74 which clamps a rear portion of the sheet metal blank B against a stationary hardened insert member 75 (see FIG. 8) which is supported in fixed position on the carriage 3 8. The clamp member 73 is operated by a double-acting fluid pressure operated cylinder 76 having a piston rod 77 on which the member 73 is mounted. The solenoid operated cylinder 76 is mounted on a plate 78 fixed on carriage 38. The purpose of the clamp member 73 is to hold the rear end of the sheet when the front sheet entering members 44 and 60 have been released at the time the carriage 37 nears the end of its forward travel and prevent any fish-tailing which might otherwise occur.

Mounted on the frame F to positively stop the carriages 37 and 38 in rear position to commence another cycle are stop members 79 and 80', respectively. Prior to the time the inserts 44 and 60 can engage with the sheet B, the sheet must be advanced fonwardly by the magnetic rolls 17 from the front of the apparatus to a locator engaging position. This position is located by the stop member 81 which is swingable from the down position in which it is shown in FIG. 5 solid lines to the raised position shown in broken lines. The stop 81 is mounted on a pair of arms 82 which are pivotally supported on a pin 83, mounted by a support plate 84 on a bracket 85 fixed to the frame plate 72. Mounted on a support arm 86 as at 87 to move the stop 81 upwardly and downwardly is a double-acting fluid pressure operated power cylinder 88 having a piston rod 89 pivotally connected as at 90 to the arms 82. When the solenoid actuated cylinder 88 is moved to advance piston rod 89 and position the stop 81 in the broken line position shown in FIG. 5, the forwardly proceeding sheet B is positively stopped and the carriage sheet entering members 44 and 60 can be swung inwardly to engaged position. Once the locators 44 and 60 have been engaged the stop member 81 may be swung downwardly, and as indicated, the rollers 17 will move the sheet B, and the carriages 37 and 38 which grip it, forwardly.

Provided to power the magnetic sheet advancing rollers 17 is a variable speed drive motor 91 having an armature shaft 92 on which a sprocket 93 is fixed, as shown in FIG. 3, to drive a sprocket 94 on a rearmost shaft 16 via a chain )5. At its opposite end the rearmost shaft 16 mounts a sprocket 96 to drive a chain 97 which is trained also around a sprocket 98 which is rotatably received on the intermediate shaft 16. Fixed to the sprocket at one end is a sleeve 99, the sleeve 99 mounting a flange 100 bolted to the outer peripheral portion of a conventional over-riding clutch generally designated 101 and having, as usual, an outer drive ring 102 and a peripherally inner drive ring (not shown). The clutch 101 may be a typical sprag-type clutch of the type manufactured by The Formsprag Company of Detroit, Mich. It is the inner ring of the clutch 101 which is fixed to and drives the intermediate shaft 16. The clutch 101 permits the over-ride which occurs when the blank B is received between the feed rolls 31 and 32 of the roll forming machine which revolve at a faster rate of speed than do the magnetic rolls 17 and thus renders the roll 17 disableable. Mounted on the opposite end of the intermediate shaft 16 is a sprocket 103 driving a chain 104, which at its opposite end, is trained around a sprocket 105 and drives the lead shaft 16.

Provided to return the carriages 37 and 38 from the position shown in chain lines in FIG. 1, to the position shown in full lines are a pair of chains 106 and 107, respectively, which mount carriage engaging fingers 108 and 109, respectively. The fingers 108 are adapted to engage dependent lugs 110 on the carriage 37 and 111 on the carriage 38, respectively. The chain 106 is trained around front and rear sprockets 1112, and the chain 107 is trained around front and rear sprockets 113. At the front end of the machine the sprockets 112 and 113 are journaled on an idler shaft 114, mounted on a bracket 115, secured to the plate 72, while, at the rear end of the machine, the sprockets 112 and 113 are fixed on a shaft 114a which is coupled as at 115a. to the output shaft of an air motor 116. The shaft 114a may be journaled by pillow blocks 117. Because an air motor is used, a slipable drive is provided which permits the fingers 108 and 109 to exert a pressure against the carriages 37 and 38 after they have been returned to rearmost positions against the stops 79 and 80, and until the new blank B has been moved against the raised stop 81 and locator members 44 and 60 have been swung into engaged position. The air motor 116 is operated to turn the shaft 114 alternately in opposite directions of rotation by a solenoid operated valve 118 (see FIG. in the usual manner.

A typical control circuit is shown in FIG. 10 to operate the valve 118 and the various power cylinders and includes advance and retract solenoids 119 and 120, respectively, for each of the cylinders 45, and 121 and 122, respectively, for each of the cylinders 55. The cylinder 76 utilizes an advance solenoid 123, and a retract solenoid 124 and the cylinder 88 an advance solenoid 125 and a retract solenoid 126. In addition to this, the valve 118 has solenoids 127 and 128 which operate the valve 118 to drive the motor 116 in one direction or the other. The solenoid 127 is energized to operate the valve 118 to drive the motor 116 in a direction to return the fingers 108 and 109 rearwardly by the contacts 129 of a switch 130 (see FIG. 8) which may be actuated as the rear carriage 38 reaches its forward position. The switch 130 also has another pair of contacts 131 which operate to energize the retract solenoid 124 of cylinder 76 and raise the vertically reciprocable clamp member 74 just before the carriage 38 reaches its foremost position. When the carriages 37 and 38 are returned rearwardly by the fingers 108 and 109, respectively, the air motor 116 may be reversed by a time-delay switch 132 (see FIG. 2), having contacts 132]) in series with the retract solenoid 128 of the valve 118, which is operated after the rocker arms 50 are swung into engaged position. The contacts 132d of switch 132 are in series with the advance solenoid 123 of cylinder 76. The advancing solenoids 119 of cylinders 45 are operated by the sets of contacts 133 and 134 of a limit switch 135 (see FIG. 7), which is actuated at the time the sheet B engages the raised sheet stop 81. At the same time a time- 8 delay switch 136 (FIG. 7) may be made by the sheet reaching the stop 81 and includes sets of contacts 137 and 138 in series with the advance solenoids 121 of the cylinders 55. The contacts 137 and 138 close a short time after the contacts 133 and 134 to insure that the locator inserts 44 are swung to engaged position before the locator members 60 move inwardly. The switch 130 also has contacts 139, 140, 1 41, and 142 in series with the retract solenoids of cylinders 45 and 122 of cylinders 55 which operate to release the advancing pressure in the cylinders at the time the fingers 108 and 109 are moved to return the carriages 37 and 38. The retract solenoid 126 of stop operating cylinder 88 is energized when the limit switch 143 (see FIG. 8) is momentarily made by the descending sheet clamp member 73. The advance solenoid of cylinder 88 is operated by a limit switch 144 (see FIG. 3) which is made when the carriage 38 reaches rearmost position.

The circuit which we have shown is only typical, and it should be understood that the machine could be operated by a motor 91 which is intermittently energized to drive a blank B after the blank B operated a proximity switch. It is further to be understood that it would not be necessary to wait for the carriage 37 to return to rearmost position before raising stop 81 and, in an operation where it is desired to have one sheet closely following another, a proximity switch or the like could be used to raise the stop 81 immediately after the preceding sheet was released.

In operation the rolls 17 advance an incoming sheet to the raised stop 81 which then halts the sheet in predetermined position. Switch 135 is actuated so that contacts 133 and 134 close and energize the advance solenoids 119 of cylinders 45 to pivot the locators 44 up into notches 25 and 26. At the same time, switch 136 is actuated and the contacts 137 and 138 are closed after a short delay and energize the advance solenoids 121 of cylinders 55 to move members 60 into the notches 28 and 29. It is desirable that the movement of members 44 be completed first of all so that the members 60 can shift the blank B laterally if necessary and securely clamp the sheet B. When the one arm 50 is swung inwardly, the contacts 132a of switch 132 close to energize cylinders 76 and move the clamp 73 (see FIG. 8) vertically to clamp the sheet against stationary clamp members 75. The carriages 37 and 38 are in this way locked to the sheet B and ready to travel with it.

First of all, however, sheet stop 81 is lowered when the member 73 operates switch 143 to energize the retract solenoid 126 of cylinder 88 (FIG. 5). The rolls 17 are then free to move the sheet B forwardly and the carriages 37 and 38, of course, move with the sheet and dictate the aligned path which it must travel to the forming mill stands. As the carriages 37 and 38 near forward position cam followers 64 and 67 are forced by the cams 64a and 67a, respectively, to pivot the levers 42 and 50 to released position against the fluid pressure force exerted by cylinders 45 and 55 and the sheet is released. As indicated earlier, by the time this occurs, with first the carriage 37 and then the carriage 38, the sheet B is well engaged in the roll stands of the roll forming apparatus. Cylinder 76 is then energized to raise clamp member 73.

Switch is operated by the rear carriage 37 reaching forward position to close contacts 129 and energize solenoid 127 so that valve 118 causes air motor 116 to drive chains 106 and 107 in a direction to effect the movement of carriages 37 and 38 to original position. At the same time, cylinders 45 and 22 are energized to release the advancing pressure and cylinder 88 is operated by the switch 144 when carriage 38 reaches rearward position to raise stop 81 once again. The chains 106 and 107 are shortly thereafter returned as has been noted.

It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention rather than as limiting the same in any way since it is contemplated that 7 various changes may be made in the various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. Apparatus for precisely feeding longitudinally ex tending sheet blanks to forming roll and like mechanism comprising: first and second relatively movable guide carriages disposed longitudinally in line and including releasable sheet gripping means for each of said carriages for gripping the sheet; guide means for guiding the carriages in an aligned precise path of travel longitudinally toward said mechanism; means for releasing the carriages from the sheet sequentially when each is near the said mechanism; and drive means for effecting movement of the carriages and sheet forwardly which permits the second carriage to continue to move forwardly to guide the sheet after the first carriage has ceased guiding the sheet.

2. The combination defined in claim 1 in which said drive means moves the sheet and thereby the carriages; the guide means mounting the carriages for reciprocating movement.

3. The combination defined in claim 1 in which said means for releasing the carriages includes operating means for releasing said sheet gripping means; and carriage position sensing means is provided in the path of each of said carriages for causing said operating means to release said sheet from each carriage as each approaches said mechanism.

4. The combination defined in claim 3 in which said sheet gripping means comprises opposed clamp members for at least one of said carriages operable to be moved into clamped engagement with opposite side edge portions of the blanks.

5. The combination defined in claim 4 in which sensing means, provided to sense the position of a blank,

operates said clamp members to grip the blank in the first place.

6. Apparatus for precisely feeding longitudinally extending sheet blanks to forming roll and like mechanism comprising: sheet gripping carriage means; rigid guide means extending longitudinally toward said mechanism and guiding the carriage means in a path of linear longitudinal travel toward said mechanism; releasable sheet gripping means for said carriage means; and drive means for drivingly engaging the sheet to move it forwardly and moving said carriage means therewith.

7. The combination defined in claim 6 in which said drive means comprises transversely extending, slipable magnetic roll means over which the sheet passes.

8. The combination defined in claim 7 in which said magnetic roll means comprises a series of longitudinally spaced magnetic roll assemblies, each driven by the other; and a motor for driving one of the assemblies.

9. The combination defined in claim 6 in which said sheet gripping means includes opposed clamp members supported by said carriage means on opposite sides of the path of a blank; and means is provided for operating the clamp member on one side of said blank to grip the blank after the opposed clamp member on the opposite side of the blank is operated to engage the blank.

10. The combination defined in claim 9 in which said blanks have precisely located notches in the side edges thereof and said first operated clamp member comprises a locator member movable in a generally vertical path relative to the carriage means and path of the blanks into an edge notch.

11. The combination defined in claim 6 in which said sheet clamping means comprises: a first locator member, shaped to recesses in the sheets and mounted on the carriage means for movement into and out of the recesses; and a second locator member mounted on the carriage means for movement inwardly toward said first member to clamp the sheet between said locator members.

12. The combination defined in claim 11 in which said first locator member is mounted for pivotal movement from a position below said sheet up into a recess and said second locator member is mounted for pivotal movement in a vertical transverse plane in, to engage the opposite edge of the sheet to move the sheet so that the first locator member is fully inserted in the recess.

13. The combination defined in claim 12 in which electrically controlled fluid pressure operated cylinders power said first and second locator members.

14. The combination defined in claim 6 in which at least a pair of longitudinally spaced first and second locator members are employed in unison as said gripping means said carriage means comprising a pair of carriages each mounting a pair of said locator members.

15. The combination defined in claim 14 in which said carriage means incorporates cam follower means for moving each of said locator members to disengaged position; and cam means at the front end of the guide means is engaged by the actuator means to disengage the locator members when the carriage means nears the front end of its travel path.

16. The combination defined in claim 6 in which separate drive means is provided for returning said carriage means at the end of a forwarding cycle.

17. The combination defined in claim 16 in which said returning means comprises: endless chain means with a lug thereon on the downstream side of the carriage means; and slippable drive means for said chain means.

18. The combination defined in claim 17 in which front and rear stops are provided for said carriage means.

19. The combination in claim 6 in which front end stop means for a new blank to be fed is mounted for movement in a path to and from a position to be engaged by the end of a new blank at a predetermined spaced distance from the sheet gripping means.

20. The combination defined in claim 6 in which gravity rollers support the sheet for travel longitudinally to the forming roll mechanism; and a rear end clamp member is supported by said carriage means for movement down into engagement with the upper surface of the sheet to prevent rear end whip thereof.

21. A method of accomplishing the aligned feeding of elongate sheet blanks, which may have longitudinal camher, and are provided with precisely located opposed recesses in their edges, to forming mechanism comprising: gripping recessed edges of the blank with sheet gripping members which engage in said recesses; applying a moving force in the sheet, and thereby pulling at least certain of the gripping members, to move them longitudinally forwardly; guiding the gripping members on both sides of the sheet in a precise linear path to prevent misalignment and side drift as the gripping members and sheet are moved forwardly; and releasing the gripping members from the recesses at the forming mechanism. 22. The combination defined in claim 21 in which the gripping members are returned in the same longitudinal path following their release from the sheet to a position in which they can grip the next sheet to be advanced.

23. Apparatus for precisely feeding longitudinally extending sheet blanks comprising: sheet gripping carriage means; downstream sheet forming mechanism including sheet transporting means for gripping the sheet after it is fed thereto and transporting the sheet forwardly; rigid guide means extending longitudinally forwardly toward said mechanism and guiding the carriage means in a precise path of longitudinal travel forwardly toward said mechanism; disableable drive means for initially effecting movement of the sheet and carriage means forwardly toward said sheet formingmechanism; and releasable sheet gripping means for said carriage means; said disableable drive means for effecting forward movement of the sheet and carriage means being driven at a speed to normally drive said sheet at a different speed than said sheet transporting means and being disabled when the leading end of the blank is brought to position to be gripped and moved by said sheet transporting means to permit said transporting means to control the speed of movement of the blank.

24. The combination defined in claim 23 wherein said blanks have notched edge recesses therein and said sheet gripping means comprise at least a pair of opposed sheet clamping members supported on said carriage means for movement transversely to said carriage means, and the path of travel of said blanks, into said notches.

References Cited UNITED STATES PATENTS 2/1934 Ladd l98180 7/1968 Pearne et al. 214-6 A. N. GOODMAN, Assistant Examiner RICHARD E. AEGERTER, Primary Examiner US. Cl. X.R. 

